1. Field of the Invention
The present invention relates in general to a method of molding a skin-covered article, and more particularly to a method of molding a skin-covered foamed article which may be used as an automobile seat cushion or the like.
2. Description of the Prior Art
Japanese Patent First Provisional Publication No. 61-280908 shows one of conventional methods for molding a skin-covered cushion for an automotive seat. In order to clarify the task of the present invention, the method of this publication will be described with reference to FIGS. 8 to 10 of the accompanying drawings.
In the drawings, a mold assembly 11 is shown as comprising an upper mold 12 and a lower mold 13. The lower mold 13 comprises a fixed mold part 13a which has a bored inner surface 13a' matching an outside surface of a seat cushion (see FIG. 10) which is to be produced, and a movable mold part 13b which has a protruded inner surface 17 matching a front surface of the produced seat cushion and is vertically movable relative to the fixed mold part 13a. The fixed mold part 13a is formed around the bored bottom thereof with a stepped seat portion 15 onto which a peripheral portion of the movable mold part 13b is adapted to be seated. A shaft 16 of a lift device (not shown) is secured to the movable mold part 13b to move the movable mold part 13b upward and downward.
The following steps are employed for molding the seat cushion.
The upper mold 12 is kept removed from the fixed mold part 13. By operating the lift device, the movable mold part 13b is lifted up beyond the fixed mold part 13a. A bag-shaped outer skin member 21, which has been turned inside out, is put on the movable mold part 13b. As is seen from FIG. 9, a center part 21a of the skin member 21, which is to cover a front surface 25a of a foamed pad member 25 which is to be molded, is tightly put on the protruded inner surface 17 of the movable mold part 13b, while, peripheral outer portions 21b of the skin member 21, which are to cover an outer surface 25b of the foamed pad member 25, are turned back and detachably fitted to the back portion of the movable mold part 13b by means of hooks 18.
Then, as is seen from FIG. 9, the movable mold part 13b is lowered to its operative position having the peripheral portion seated on the stepped seat portion 15 of the fixed mold part 13a. Then, a suitable amount of liquid foamable material 25' for foamed plastic, such as urethane foam or the like, is poured into the cavity of the lower mold 13 thus coupled. Then, as is seen from FIG. 10, the upper mold 12 is put on the lower mold 13 to close the cavity.
After the foamable material 25' is hardened to a sufficient level, the same, viz., the foamed pad member 25, is removed from the molds 12 and 13 along with the skin member 21. Then, the peripheral outer portions 21b of the skin member 21 are turned front to cover the outside surface of the foamed pad member 25.
However, the above-mentioned method has the following drawbacks due to its inherency.
That is, it tends to occur that, during pouring of the liquid foamable material 25' into the mold, a part of the same leaks out through the skin-pressed area which is defined between the stepped seat portion 15 of the fixed mold part 13a and the peripheral portion of the movable mold part 13b. This undesired leakage becomes much more severe when the skin member 21 is of a multi-plys type, such as a laminated sheet material including a plurality of urethane foam layers. The leakage induces not only deterioration in external appearance of the product but also production of an abnormally hardened part on the product.